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Possibility of reservoir-induced seismicity in the Garhwal Himalaya
3A greater in the second case, even though the stress on the already fractured segment has been dropped to a very low level.
921019 Forced anti-plane vibrations at the surface of an inhomogeneous half-space Vrettos, C
Soil Dynam Earthq Engng VIO, N5, July 1991, P230-235 921015 Rupture nucleation on unfavourably oriented faults Sibson. R H
Bull Seismol Soc Am 1/80, N6, Dec 1990, P1580-1604 Depending on its attitude in the prevailing stress field, a fault may be favourably oriented, unfavourably oriented, or severely misoriented for frictional reactivation. It is demonstrated that in compressional stress regimes unfavourably oriented faults are only likely to stay active where fluid pressures are elevated well above hydrostatic values. There is considerable field evidence to support this. For severely misoriented faults, fluid pressure must exceed the least principal stress (i.e. this becomes tensile). Fluid pressure triggering of earthquakes then becomes probable.
921016 Probabilistic seismic risk analysis in the Taiwan area based on PGA and spectral amplitude attenuation formulas Loh, C H; Yeh, Y T; Jean, W Y; Yeh, Y H
Engng Geol V30, N3/4. June 1991, P277-304 The geology, tectonics, and seismicity of Taiwan are first summariscd. A method is presented for seismic hazard analysis of active faults using a fault-rupture model and a point-source model. The annual probability of exceedance at a given site is calculated based on peak ground acceleration attenuation formulae, and the uniform hazard spectrum is determined based on spectral amplitude attenuation formulae. A detailed study of hazard parameters is made. The suitability of this approach is investigated for two specific sites.
The dynamic response to a time harmonic tangential line force on the surface is examined for an inhomogeneous linear elastic half space, with density constant and shear modulus increasing with depth according to a bounded function. Displacement distribution at the surface is derived using the classical Fourier transform method. The resulting integral expressions are evaluated by residue integration. The solution for the homogeneous half space is a special case. Displacement contributions of the particular vibrational modes are compared for realistic soil profiles and frequencies.
921020 Scattering of plane SH-wave by cylindrical canyon of arbitrary shape Liu Diankui; Han Feng
Soil Dynam Earthq Engng VIO, NS, July 1991. P249-255 The method of functions is used to analyse the scattering of SH waves by a two dimensional canyon of arbitrary shape. Examples are presented for semicircular, semielliptical, and triangular valleys. The technique can be applied to evaluate the effect of topography on the surface displacements along a two dimensional canyon.
921021 Principal geotechnical aspects of the 1989 Loma Prieta earthquake Seed, R B; Dickenson, S E; Idriss, I M
Soils Found V31. NI. March 1991. PI-26 921017 Possibility of reservoir-induced seismicity in the Garhwal Himalaya Chander, R
Engng GeM V30, N3/4, June 1991, P393-399 Many large dams are planned or under construction in the Himalaya. Available evidence suggests RIS cannot be discounted for the Himalaya as a whole. Although none has yet been reported in the Garhwal Himalaya, small to moderate earthquakes have been recorded at depths consistent with those for most RIS events. Reactivation of strike slip and reverse faults by reservoir impoundment is possible, and even a thrust fault may be destabilised.
921018 Mechanics of earthquake afterslip Marone, C J; Scholtz, C H; Bilham, R
J Geophys Res V96, NB5, May 1991, P8441-8452 Surface slip from large earthquakes often continues for long periods subsequent to the earthquake. A model for this afterslip has been developed, based on rate and state variable frictional laws. This approach was selected because of the success of these laws in describing results of a variety of laboratory frictional experiments and observations which indicate that the upper regions of many well-developed frictional faults show velocity strengthening frictional behaviour.
The magnitude 7.1 earthquake occurred when a segment of the San Andreas fault ruptured over a length of approximately 45km. Effects of local site conditions on ground reactions have been examined. Damage is concentrated around sites underlain by deep and generally cohesive deposits, which serve to amplify bedrock shaking. Liquefaction occurred generally in areas previously identified as liable to liquefy. Slope instability was manifest as slides and rock falls and failures by slumping of engineered fills. Correlation between these phenomena and geological and geotechnical features is discussed.
921022 Pore-pressure variation as a precursory phenomenon: the need for and a list of supplementary data Kumpel, H J
Teetonophysics V193, N4, July 1991, P377-383 Pore pressure, a component of total stress, has a strong influence on failure of rocks. Pore pressure variations therefore have an important role in the earthquake cycle. Well level fluctuations reflect possible pore pressure anomalies prior to earthquakes. Evaluation of the reliability of hydrologic precursors and the appropriate fault models is dill.cult because of sparseness and doubtful quality of some data. Improvements to documentation of hydrologic precursors are proposed, including information on construction of the well, hydrologic environment,pore fluid, signals measured, and earthquake related data.
'~ 1992 Pergamon Press plc. Reproduction not permitted
921019 Forced anti-plane vibrations at the surface of an inhomogeneous half-space Vrettos, C
Soil Dynam Earthq Engng VIO, N5, July 1991, P230-235 921015 Rupture nucleation on unfavourably oriented faults Sibson. R H
Bull Seismol Soc Am 1/80, N6, Dec 1990, P1580-1604 Depending on its attitude in the prevailing stress field, a fault may be favourably oriented, unfavourably oriented, or severely misoriented for frictional reactivation. It is demonstrated that in compressional stress regimes unfavourably oriented faults are only likely to stay active where fluid pressures are elevated well above hydrostatic values. There is considerable field evidence to support this. For severely misoriented faults, fluid pressure must exceed the least principal stress (i.e. this becomes tensile). Fluid pressure triggering of earthquakes then becomes probable.
921016 Probabilistic seismic risk analysis in the Taiwan area based on PGA and spectral amplitude attenuation formulas Loh, C H; Yeh, Y T; Jean, W Y; Yeh, Y H
Engng Geol V30, N3/4. June 1991, P277-304 The geology, tectonics, and seismicity of Taiwan are first summariscd. A method is presented for seismic hazard analysis of active faults using a fault-rupture model and a point-source model. The annual probability of exceedance at a given site is calculated based on peak ground acceleration attenuation formulae, and the uniform hazard spectrum is determined based on spectral amplitude attenuation formulae. A detailed study of hazard parameters is made. The suitability of this approach is investigated for two specific sites.
The dynamic response to a time harmonic tangential line force on the surface is examined for an inhomogeneous linear elastic half space, with density constant and shear modulus increasing with depth according to a bounded function. Displacement distribution at the surface is derived using the classical Fourier transform method. The resulting integral expressions are evaluated by residue integration. The solution for the homogeneous half space is a special case. Displacement contributions of the particular vibrational modes are compared for realistic soil profiles and frequencies.
921020 Scattering of plane SH-wave by cylindrical canyon of arbitrary shape Liu Diankui; Han Feng
Soil Dynam Earthq Engng VIO, NS, July 1991. P249-255 The method of functions is used to analyse the scattering of SH waves by a two dimensional canyon of arbitrary shape. Examples are presented for semicircular, semielliptical, and triangular valleys. The technique can be applied to evaluate the effect of topography on the surface displacements along a two dimensional canyon.
921021 Principal geotechnical aspects of the 1989 Loma Prieta earthquake Seed, R B; Dickenson, S E; Idriss, I M
Soils Found V31. NI. March 1991. PI-26 921017 Possibility of reservoir-induced seismicity in the Garhwal Himalaya Chander, R
Engng GeM V30, N3/4, June 1991, P393-399 Many large dams are planned or under construction in the Himalaya. Available evidence suggests RIS cannot be discounted for the Himalaya as a whole. Although none has yet been reported in the Garhwal Himalaya, small to moderate earthquakes have been recorded at depths consistent with those for most RIS events. Reactivation of strike slip and reverse faults by reservoir impoundment is possible, and even a thrust fault may be destabilised.
921018 Mechanics of earthquake afterslip Marone, C J; Scholtz, C H; Bilham, R
J Geophys Res V96, NB5, May 1991, P8441-8452 Surface slip from large earthquakes often continues for long periods subsequent to the earthquake. A model for this afterslip has been developed, based on rate and state variable frictional laws. This approach was selected because of the success of these laws in describing results of a variety of laboratory frictional experiments and observations which indicate that the upper regions of many well-developed frictional faults show velocity strengthening frictional behaviour.
The magnitude 7.1 earthquake occurred when a segment of the San Andreas fault ruptured over a length of approximately 45km. Effects of local site conditions on ground reactions have been examined. Damage is concentrated around sites underlain by deep and generally cohesive deposits, which serve to amplify bedrock shaking. Liquefaction occurred generally in areas previously identified as liable to liquefy. Slope instability was manifest as slides and rock falls and failures by slumping of engineered fills. Correlation between these phenomena and geological and geotechnical features is discussed.
921022 Pore-pressure variation as a precursory phenomenon: the need for and a list of supplementary data Kumpel, H J
Teetonophysics V193, N4, July 1991, P377-383 Pore pressure, a component of total stress, has a strong influence on failure of rocks. Pore pressure variations therefore have an important role in the earthquake cycle. Well level fluctuations reflect possible pore pressure anomalies prior to earthquakes. Evaluation of the reliability of hydrologic precursors and the appropriate fault models is dill.cult because of sparseness and doubtful quality of some data. Improvements to documentation of hydrologic precursors are proposed, including information on construction of the well, hydrologic environment,pore fluid, signals measured, and earthquake related data.
'~ 1992 Pergamon Press plc. Reproduction not permitted